Due to superior wear and corrosion resistance, polymer-lined pipes and fittings have been used in many aggressive slurry services in the oil sands mining industry. Rubbers and polyurethanes are the main polymeric liner materials currently being used. Liner thickness is commensurate with length of the pipe run, and can exceed 1 inch in very long pipe runs. However, liner wear still occurs, and in particular, the inlets and outlets often experience the most serious liner wear. This is mainly due to pipe misalignment where the resultant step change in pipe inside diameter (ID) can cause so-called ‘liner wash-out’ due to either direct impingement from the slurry particles (prior art FIG. 1A) or slurry turbulence. The wash-out area is localized, normally less than a foot from the pipe connection between the upstream pipe (UP) and the downstream pipe (DP). Liner wear is often accelerated in that localized wear zone, resulting in early retirement of the spool even though most areas are in serviceable condition.
When there is step-change in inside diameter at pipe connection due to different inside diameters (IDs) of mating pipes (prior art FIG. 1B), transition rings can be used for smooth ID transition. Transition rings use abrasion and wear resistant alloy linings such as tungsten carbide, which introduces significant cost increase. Also, transition rings are flange-connected, thereby incorporating more pipe connection points with a resulting increase in the possibility of ID mismatch.